Ditopic binding of various dinitrogen compounds to three bisporphyrin molecular tweezers with spacers of varying conformational rigidity, incorporating the planar enediyne (1), the helical stiff stilbene (2), or the semi-rigid glycoluril motif fused to the porphyrins (3), are compared. Binding constants K a = 10 4 -10 6 M´1 reveal subtle differences between these tweezers, that are discussed in terms of porphyrin dislocation modes. Exciton coupled circular dichroism (ECCD) of complexes with chiral dinitrogen guests provides experimental evidence for the conformational properties of the tweezers. The results are further supported and rationalized by conformational analysis.
We have developed a microwave-assisted, reagent-free method for the efficient primary purification of MW and SW carbon nanotubes that is extremely fast compared to previously reported processes. The treatment dissociates and disperses non-nanotube carbon in an organic solvent to yield very pure carbon nanotubes within a few minutes of heating and a simple filtration, without the involvement of acidic/oxidative reagents. According to thermogravimetric analysis, Raman and IR spectroscopy, as well as scanning and transmission electron microscopy, the process yields pure nanotubes with a low degree of defects.
A new [60]fullerene dumbbell consisting of two fulleropyrrolidines connected to a central ferrocene unit by amide linkages has been prepared and fully characterized by elemental analysis, (1)H NMR, UV/Vis, fluorescence and mass spectrometry. The electrochemical properties as determined by cyclic voltammetry show ground state electronic communication between the ferrocene and the fullerene units. In addition, the preparaton of a ferrocene building block for an alternative linking approach is presented.
SWNTs and MWNTs have been non-covalently functionalized with glycosides in a reversible manner, and fluorescence titrations have been used to quantify the formed supramolecular assemblies which for SWNTs exhibits increased water solubility.
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